\\[-1.8ex] Soil Heterogeneity & $-$0.102$^{*}$ & $-$0.068$^{**}$ & $-$0.057$^{**}$ & $-$0.040 & $-$0.049$^{*}$ & $-$0.050$^{*}$ \\ 
  & (0.053) & (0.028) & (0.027) & (0.025) & (0.027) & (0.030) \\ 
\\[-1.8ex] 
Observations & 62,905 & 62,905 & 62,905 & 62,905 & 62,905 & 62,905 \\ 
R$^{2}$ & 0.024 & 0.096 & 0.108 & 0.172 & 0.242 & 0.341 \\ 
